One of the biggest problems Cannabis growers face is from Insects. And we are not alone. It is estimated that over 5% of the entire worlds crops are lost to spider mites alone each year. And there are countless other bugs (they hate it when I call them that) that can bring us grief. And for many the only solution has been using toxic chemical insecticides routinely or at least as the last resort.
If a person eats something mildly toxic, the body has numerous systems for scavenging and protecting the body from harm. But the lungs have no defenses whatsoever, and anything you inhale goes straight into the blood stream. So spraying toxic chemicals on Cannabis is especially problematic, because Cannabis is most commonly ingested through the lungs. In addition, many compounds that are not toxic, can become toxic after they are burned.
So it is extremely important to not use chemical insecticides on flowering cannabis. So what do you do? Discover the magic of surfactants, better know as soap.
No I know it’s not a new idea to use soap on bugs, but most people get only marginal results using soap, and so in the end they go back to chemicals. However, there is a very precise method that must be employed with soap to get consistent results, and when employed it kills virtually ALL insects, every time. (And yes there are a few tenacious species that seem to have a trick up there sleeve that preserves them, but they are few.)
So what follows is the magic formula for using soap to kill bugs. And it also retards powdery mildew and other leaf fungi.
Part one: Surfactants
You need to use a surfactant that is organic based so it has the least likelihood of creating nasty combustion bi-products when burned. If it’s a plant based surfactant, when burned it makes the same stuff burning cannabis makes.
In my experience the most effective and least toxic surfactant is Yucca Extract. Yucca has been the ingredient that makes Root Beer frothy for over a century, so its safety is well proven. (But frankly, recently I have occasionally used Trader Joes organic plant extract based dish soap with good results.) But each surfactant performs differently, so find one and stick to it. (no reverse pun intended)
The way soap kills insects:
All insects breathe air through tiny pores in their skin (for caterpillars etc) or exoskeleton (for the armored guys) called spiricles. If an insect is simply immersed in water, these pores and other aspects like hairs etc. trap enough air in tiny bubbles to respirate the insect for quite a while. (A relatively smooth grasshopper will survive underwater for several minutes)
But when you add enough surfactant to the water, it lowers the surface tension (slipperiness) of the water and releases those bubbles, and the insect rapidly suffocates. It releases dirt in the same way and that’s how it cleans. So the trick in using surfactants is to use just enough to insure you completely cover the leaf, and enough to insure the air bubbles on the insect are released.
Part two: Sticker / spreader (better known as oil)
The main reason people do not get good results with soap is they only use soap and water. If you do just use soap, especially on waxy plants like Cannabis or shiny tropicals, etc.., the soapy water completely covers the leaf and the insects, but then it immediately runs off, leaving the leaf and the bugs uncoated. So to be effective, surfactants must be used with a sticker spreader, typically organic based oils.
Virtually any oil will work, but they work best when they emulsify, i.e. dissolve into the water instead of just remaining in little clumps. But soap acts to emulsify oil, so if you use enough soap, most oils will emulsify in water.
The most common sticker / spreader oil used in the cannabis industry is Neem oil, mostly because it makes various bugs including Spider Mites stop or slow eating. But ANY oil will work. Olive oil, Corn oil, you name it. The KEY, is that you use it correctly. (There are also organic sticker/ spreader products available commercially that emulsify rapidly into a milky solution that perform better than simple oil, but any oil will work if you follow this process.)
First you have to use enough soap to not only instantly cover the leaf, but also to emulsify the oil. This will take experimentation with every combination of plant, soap, and oil. But then you have to use enough oil that when the spray completely covers the leaf, it remains on the leaf in a thin coating. Thinner is better, and this is where the choice of oils can make a difference.
You see if the viscosity of the Soap/water/oil mix is too high, (ie too thick) it won’t be able to readily flow around and under the bugs, and instead will just form a bubble over them. So you want to use as thin an oil as possible to reduce the viscosity, while still leaving a thin coating on the leaf and bug without complete run-off.
Sounds complicated? It isn’t. Just follow these steps.
1) Add soap to water until it foams vigorously. Mix.
2) Add oil to water. Start with around 1 oz per gallon mix. Shake vigorously. If the suds disappear, add more soap until you see suds again.
3) Spray a sample leaf and see if the leaf instantly coats and leaves no dry spots from run-off. If it does, add more soap, and repeat. Also look carefully at the way the solution runs off. Does it flow like plain soapy water? If it looks noticeably thicker, try to use a thinner oil or shake it better to fully emulsify the oil.
4) Wait until the leaf dries and identify whether it has a fine coat of oil (shine) covering it completely. If it still looks dry i.e. unchanged, add 50% more oil and repeat the process.
5) You can add foliar feed, or bacteria to this mix, but again, the key is to make sure the consistency will kill the bugs.
6) Finally, if your using it on a flowering Cannabis plant, check the PH with a dry surface PH meter and keep it around 6.5 or you can make the little stamens on the buds turn brown, and if much lower than 6.5 the leaves will wilt just a little. But if this happens, don’t fear, they will be fine in just day or so.
7) Spray you plants and then inspect the next day (no longer because the eggs can hatch and fool you into thinking they survived the spray. If you see living bugs, you know your mix was either too thick, or it didn’t cover properly.
Different insects require different application regimes depending on how long their eggs take to hatch etc.. but for the number one nemesis of Cannabis growers, namely the two-spotted spider mite, (or as many of us call them, The Borg, for resistance can often appear to be futile) 3 rounds of spray 3-4 days apart will generally clean them out. The hotter the temp, the shorter the duration between applications. The colder the longer.
Special Tip from Silas: You can also add a little Bacillus Subtilis, ie. brand name Serenade (1 oz per gallon) found in your local garden stores, and a 5-10 ml / gallon of Botanicare Sweet, and extend the Powdery Mildew AND Botrytis bud mold protection to as long as 4 weeks from only one spray application!
So this is the SCIENCE of using surfactants to kill plant eating insects, (and fungi) and if done correctly, it will kill virtually all insects consistently and with no residual toxicity on the end product, even within days of harvest. If you do plan to spray within 3-4 weeks of harvest, I recommend you use only a soap and oil combination you would be willing to eat, such as Yucca Extract and some kind of THIN salad oil. Any other time, or in Veg mode, any organic products will work. Personally, I use Yucca extract and Neem oil, and a secret organic ovicide (kills eggs) ingredient I will discuss in a later article, and I don’t spray within 3 weeks of harvest.
To those who grow we salute you!